title: Influence of two hop (Humulus lupulus L.) varieties on in vitro dry matter and crude protein degradability and digestibility in ruminants.
abstract: BACKGROUND
  Hop cones contain several antimicrobial substances. The aim of the study was to determine the effects of two hop varieties, Aurora and Dana, on substrate (diet for a dairy cow, producing 30 kg milk daily) in vitro dry matter (DM) and crude protein (CP) degradability and digestibility.
  
  
  RESULTS
  In the in vitro trial freshly ground hops were added to the buffered rumen fluid in concentrations simulating the cow's daily intake of 50, 100 and 200 g of hops. Increasing the concentration of hops decreased (P < 0.05) both the average in vitro DM degradabilities of substrate from 725 to 592, 553 and 481 g kg(-1), respectively, and in vitro CP degradabilities of substrate from 752 to 566, 561 and 478 g kg(-1), respectively. The reduction of in vitro DM and CP degradability is counterbalanced by the (invariable) in vitro DM and CP digestibility. The difference between CP digestibility and degradability represents an estimate of the amount of rumen 'bypass' protein which increased with increasing concentration of hops from 172 to 454 g kg(-1).
  
  
  CONCLUSIONS
  Decreased DM and CP degradability and increased amount of rumen 'bypass' protein could lower the amounts of protein required by high-producing ruminant animals. However, this supposition needs a validation with in vivo trials.
authors.affiliation: University of Ljubljana, Biotechnical Faculty, Department of Animal Science, Domžale, Slovenia.
authors.forename: Andrej
authors.initials: A
authors.lastname: Lavrenčič
authors.forename: Alenka
authors.initials: A
authors.lastname: Levart
authors.forename: Iztok Jože
authors.initials: IJ
authors.lastname: Košir
authors.forename: Andreja
authors.initials: A
authors.lastname: Cerenak
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle; D004032:Diet; D004043:Dietary Fiber / Q000378:metabolism*; D004044:Dietary Proteins / Q000378:metabolism*; D019587:Dietary Supplements; D004063:Digestion; D005260:Female; D035264:Flowers; D027582:Humulus / Q000737:chemistry* / Q000145:classification; D009751:Nutritional Requirements; D028321:Plant Preparations / Q000494:pharmacology*; D010940:Plant Proteins / Q000378:metabolism; D059748:Proteolysis / Q000187:drug effects; D012417:Rumen / Q000187:drug effects* / Q000378:metabolism; D013045:Species Specificity
chemical_list: D004043:Dietary Fiber; D004044:Dietary Proteins; D028321:Plant Preparations; D010940:Plant Proteins
keywords: crude protein; hops; in vitro degradability; in vitro digestibility; rumen